i'm used to other keyboards where increasing the keyboard tracking makes the lower notes darker and higher brighter...
That's how it works on the Pro 2 as well, but as someone else mentioned you may need to turn your cutoff down to compensate after adding tracking. A value of 64 should track 1V/Oct. You can set Filter 1 to self-resonate and confirm.
Here's what I suspect is going on, and why it seems to make your patch brighter at first. I think DSI's method of applying tracking references the lowest note possible and sets filter tracking there starting at zero, then it goes up the scale. Other synths might pick C2 or C3 as the "zero point", and it goes up or down accordingly. Same result really, you just have to set your initial cutoff lower on the Pro 2.